To provide a sewing thread that is excellent in high-speed sewability and automatic sewing characteristics. A sewing thread includes a plurality of under-twisted yarns provided with upper-twist, the yarns each being composed of a sheath-core structure yarn composed of two or more multifilament yarns, wherein part of the sheath-core structure yarn protrudes as loops on a yarn surface, the loops being composed of 50 to 300 loops/m with 0.7 to less than 1.2 mm length and 10 or less loops/m with 1.2 mm or more length, and wherein the yarns have a strength of 4 to 6 CN/dtex.